For example, JP-A-3378883 discloses an occupant protection apparatus for a vehicle having an enhanced protection performance for an occupant when the vehicle causes multiple collision. Specifically, according to JP-A-3378883, the occupant protection apparatus activates a pre-tensioner when the vehicle causes collision. Further, the occupant protection apparatus continues activation of the pre-tensioner for a period, in which the vehicle possibly causes multiple collision, without deactivating the pre-tensioner. The occupant protection apparatus of JP-A-3378883 continues activation of the pre-tensioner when the vehicle causes collision. It is noted that, the vehicle possibly cause both front collision and rear collision in multiple collision. Accordingly, an occupant protection apparatus related to front collision and another occupant protection apparatus related to rear collision are desirably activated separately with respect to front collision and rear collision.
In JP-A-3378883, the occupant protection apparatus (pre-tensioner) related to rear collision is activated when the vehicle causes front collision in multiple collision. Accordingly, in multiple collision, the pre-tensioner is already activated when the vehicle further causes rear collision subsequent to the front collision. Accordingly, the pre-tensioner may not be appropriately activated when the vehicle causes the subsequent rear collision, even though the pre-tensioner is desirably activated in the rear collision. Therefore, erroneous activation of the occupant protection apparatus related to rear collision needs to be avoided when the vehicle causes front collision.
In general, in multiple collision, the vehicle first collides another vehicle running in front of the vehicle to cause front collision, and subsequently, the vehicle is collided by another vehicle running from the behind of the vehicle to cause rear collision. Accordingly, an occupant protection apparatus related to rear collision needs to be steadily activated subsequent to front collision.